Learn Ling on Lingvist

Lingvist is a good app for anyone who is busy but wants to quickly learn a new language. The app focuses on around 5000 words in each language to help you learn at an accelerated pace, the theory behind it is that these words are all that you need. Since its inception in 2014, it has been downloaded by over 6 million people.
Price: $9.99/month
Devices: Android, iPad, iPhone, and Web